Dr Nisticò and colleagues from Italy adopted the twin method to evaluate celiac disease.
The researchers aimed to disentangle the genetic and environmental components of susceptibility to the disease.
The research team estimated disease concordance rate by zygosity, and human leukocyte antigen (HLA) genotypes.
Discordance times, progression rates to disease, and heritability were also assessed.
The team cross-linked the Italian Twin Registry with the membership lists of the Italian Celiac Disease Association.
The team then recruited 23 monozygotic, and 50 dizygotic twin pairs with at least 1 affected member.
| Monozygotic co-twins had a 70% probability of symptomatic celiac disease within 5 years|
Zygosity was assigned by DNA fingerprinting, and human leukocyte antigen-DQ and DR alleles were genotyped.
Disease status was ascertained by antiendomysial, anti-human tissue transglutaminase antibodies, and bowel biopsy.
The team found that concordance was significantly higher in monozygotic than in dizygotic pairs.
Concordance was not affected by sex or human leukocyte antigen genotype of the co-twin.
The researchers observed that being monozygotic was significantly associated with the occurrence of celiac disease.
In 90% of concordant pairs the discordance time was 2 years.
Monozygotic and dizygotic co-twins had a 70% and 9% cumulative probability of symptomatic or silent forms of celiac disease, respectively, within 5 years.
The team applied under additive genetic, common, and unshared environmental factors models to estimate heritability.
With celiac disease population prevalences of 1 in 91 and 1 in 1000, heritability estimates were 87% and 57%, respectively.
Dr Nisticò's team concluded, “Monozygotic pairs have a high probability of being concordant, regardless of sex or human leukocyte antigen genotype.”
“Most of the affected co-twins receive a diagnosis within 2 years.”
“A remarkable proportion of phenotypic variance is due to genetic factors.”